Back on main topic - I've used a budget 4 cam DVR from y3k.com, and E4 I think - it was a terrible generic Chinese load of rubbish, could recommend it - bad quality and really full of bugs.
Recently swapped for a Kguard SHA104 4 camera job - on sale on plent of web shops and its really good for the price, remote network viewer, PTZ, motion detection (that works) and easy to backup.